Mechanical vibrator system



March 19, 1935. P. F. SCOFIELD MECHANICAL VIBRATOR SYSTEM 2 Sheets-Sheet1 Filed Jan. 2, 1934 SOFT METAL all! all alidflllll vla IIIII'AIIIINVENTOR, PHIL/P F. SCOF/ELD. BY

A TTORNE Y March 19, 1935. P. F." SCOFIELD 1,994,793

MECHANICAL VIBRATOR sYs'rsu' Filed Jan. 2, 1934 2 Sheets-Sheet 2 7 {IINVENTOR, 3/ I I PHIL /P E SCOF/EL o.

{30 B Y Z7 ATTORNEY Patented Mar. 19, 1935 UNITED STATES PATENT OFFICEMECHANICAL VIBRATOR SYSTEM Application January 2, 1934, Serial No.705,039

6 Claims.

My invention relates to a mechanical'vibrator and means and method ofoperation, with particular reference to a vibrator having enclosedcontacts operated by a cyclical shaking.

Among the objects of my invention are: to provide a mechanical vibratorwherein contact points are protected from excessive arcing; to provide amechanical vibrator wherein contacts are surrounded by a substantiallyoxygen free atmosphere; to provide a mechanical vibrator wherein thecontacts are enclosed in a vitreous envelope; to provide a mechanicalvibrator having a movable contact adapted to be mechanically shaken toalternately touch stationary contacts; to provide a mechanical vibratorwherein a movable contact is adapted to alternately touch stationarycontacts, the movable contact being supported by a member deformablebeyond the elastic limit of the supporting material within its range ofmotion; to provide a means and method of generating or rectifyingalternating current by the use of a mechanical vibrator; to

provide a mechanical vibrator assembly enclosed within a vitreousenvelope; and to provide a combination of a vibrator contact assemblyenclosed within a vitreous envelope with mechanical means external ofsaid envelope for shaking the assembly to produce alternating currentgeneration or rectification.

Other objects of my invention will be apparent or will be specificallypointed out in the description forming a part of this specification, butI do not limit myself to the embodiment of the invention hereindescribed, as various forms may be adopted within the scope of theclaims.

This application deals only with the combination of enclosed contactswith their means for shaking. The circuits which are herein shown butnot claimed are the subject of my application entitled Vibrator andcircuit therefor, Serial No. 713,123, filed February 27, 1934.

In the drawings which illustrate a preferred embodiment of my contactassembly, together with several embodiments of a means for shaking oneor more of the contact assemblies:

Figure 1 is a longitudinal sectional view of a contact assembly tube.

Figure 2 is a longitudinal sectional view of the same tube taken along aplane at right angles to that of Figure 1, taken as indicated by theline 2-2 in Figure 1.

Figure 3 is a cross sectional view taken as indicated by the line 33 inFigure 2.

Figure 4 is a side view in elevation of a. single tube, together withits shaking mechanism.

, equipment.

Figure 5 is a top view, somewhat diagrammatical, of the arrangement usedto operate two tubes simultaneously.

Figure 6 is a top view, also diagrammatical, of the linkage used tooperate three tubes for three phase rectification or generation.

Figure '7 is a circuit, diagrammatical and reduced to lowest terms,wherein my tube may be used to generate alternating current from adirect current source.

With the increasing popular use of low powered radio receiving andtransmitting sets, particularly those adapted for operation at extremelyhigh frequencies, the problem of high voltage D. C. for plate supply hasbecome increasingly important. Dry batteries do not last long undertransmitting loads. Furthermore, these new radio sets are so light inrelation to their range that they are used, to a large extent, asportable They are also installed in places where alternating current isnot easily available. Automobiles, small boats, airplanes and ships ofany size are examples of locations where alternating current is noteasily available.

It is, of course, possible to install motor generators in such places,or dynamotors. These machines are expensive and often times ineflicientand wasteful of power.

There has been, recently, a trend toward mechanical vibrators for thecyclical chopping of direct currents so that the resultant alternatingcurrent may be used, either before or after voltage step-up, fortransmitting and receiving sets. It has been customary, however, to usevibrators of the tuned reed type operating in air, and the reed hasusually been electrically oscillated. Considerable trouble, however, hasbeen encountered with tuned reed vibrators. They are prone to arc, butto my mind their greatest drawback is their tendency to bounce uponmaking contact. This proclivity is due to the resonant suspension of themoving contact, and the bouncing gives rise not only to serious arcingand consequent wear of the contacts but also to vagaries in wave form,and in many cases to the generation of interference. A positiveelectrical contact is highly to be desired in a mechanical vibrator,together with a clean break. Any hesitation, either at the making orbreaking, will not only cause noise in the form of audio frequencysputtering, but will also cause an are which, in cooperation withassociated circuits, may easily set up undesirable high frequencyoscillations.

Still another objection to tuned reed vibrators is that their period ofvibration changes with temperature. They are also subject to operationaldisturbance when used in moving vehicles having various periods ofvibration of their own, which may be transmitted to the reed, or whensuch vehicles encounter bumps.

The mechanical vibrating system of my inven tion is not subject to thediificulties as described above, and the apparatus comprises, in broadterms, the combination of a pair of spaced stationary contacts and amovable contact supported between the stationary contacts. I prefer tomount the movable contact on a soft metal support and have the range ofmotion of the movable contact sufiicient that the support is deformedduring the passage from one contact to the other, the deformation beingbeyond the elastic limit of the material. Therefore the movable contactand stationary contact, when they are in touching position, are heldtightly together by the strength of the metal, thereby preventingbounce. The motion of the movable contact is preferably caused by amechanical shaker, a reciprocating motion being applied in line with thepath of the movable contact, this motion being cyclical and of course ofsuflicient strength to overcome the elastic force tending to hold themovable contact touching the stationary contact. In order to furthersafeguard the operation of the device, I prefer to mount theentire'contact assembly in a vitreous envelope and to operate thecontacts in a space substantially free from oxygen. The preferred methodof doing thisis to evacuate the envelope and either leave it in anevacuated condition or to refill the envelope with an inert gas.

A better understanding of my vibrator system may be had by reference tothe figures wherein an envelope 1, preferably cylindrical in shape, isprovided with a reentrant stem 2 having a pinch 3 on its inner end. Theentire tube stem and pinch are quite similar in their preferred form tothe envelopes commonly used in the construction of thermionic tubes, infact the entire contact assembly tube may be made on machines adapted toproduce vacuum tubes. The pinch 3 has sealed therethrough a pair ofstationary contact supports 4-4. While the actual shape of the sectionof these supports is immaterial as long as they are exceptionally stiffso as to be nonvibrating, I prefer to form them as shown of strong Tsection, with their bases thoroughly imbedded in, or even passingthrough, the pinch. Stationary contact leads 5 are extended from thesupports 4-4 to facilitate outside connections. The length of theportion of the supports 4-4 which extends into the inside of the tubemay well be extremely short, even shorter than shown in the drawings ifdesired, in order that the supports 4-4 may not have any extensivevibratory periods. The outer ends 6-6 of these supports carry opposedstationary contacts 7-7 spaced by the short gap.

The stationary contacts 7-7 preferably have parallel planar faces,although they may be slightly beveled to compensate for the aredescribed by the movable contact. This movable contact 8 is positionedbetween the two stationary contacts and has separate faces opposing thefaces of each of the stationary contacts. The movable contact ispositioned on a cross bar 9. This cross bar is of relatively heavymaterial and not substantially deformable under the forces available inthe operation of the tube. Each of the opposite ends of this cross baris welded to movable contact supports 10-10 extending toward the stem,and in the neighborhood of the base of the stem, welded to a stem clamp11. The stationary contact supports are preferably formed from a soft,easily deformable metal, and in the treatment of the tube during thepumping operation, are thoroughly annealed. I have found that softcopper forms an excellent support, as it may be continuously deformedwithout danger of breaking during a commercially practical life. Astationary contact lead 14 passes through the pinch 3, and is bent tofollow along the stem to make contact with the movable support clamp 11.

After the contacts have been assembled and mounted as described, thetube is preferably exhausted, left that way, or filled with an inertgas, the exhaust tube seal tip being designated by the numeral 12.

A pivot band 15 is then placed around the outside of the tube,concentrically located with respect to the internal movable supportclamp, and carries thereon trunnions 16-16. The outwardly extendingtrunnions 16-16 have a common axis which passes through the tube atright angles to the direction of motion of the-movable contact.

On the other end of the tube is positioned an operating clamp 1'7,substantially in the plane of the contacts, and having a connectionlip18 projecting therefrom in line with the three contacts. The tube isthen mounted as shown in Figure 4. The trunnions are inserted in abearing bracket 19 with the exhaust tip pointing downwardly. The bearingbracket is held in position by an upright standard 20 attached to asuitable base 21. Also mounted on the base is a motor 22 carrying at oneend a crank 23. This crank has a connecting rod 24 interconnecting thecrank pin of the motor with the operating lip 18 of the tube.

The device is then ready for mechanical operation. When the motor 22 iscaused to rotate, the crank arm causes the contact end of the tube tooscillate back and forth on the trunnions 16-16. As the motion isapplied in line with the path of the movable contact, the movablecontact will tend to stand still as the stationary contacts are forcedtoward it. In order for the movable contact to touch the stationarycontacts, the support will be deformed, but as the material of thesupport is soft the deformation will be beyond the elastic limit of thematerial, and when the contacts touch there is no tendency for the twocontacts to spring away again to cause a break. The movable contact willbe carried along touching the stationary contact until the direction ofmotion of the tube as a whole is reversed, whereupon the movable contactwill leave the one stationary contact and go to the other, deformingbeyond its elastic limit during its passage so that it will hold againstthe other contact during the return journey. I have found that thisarrangement gives an exceptionally clean and snappy make and break, withno tendency to bounce whatsoever.

A typical circuit which may be used with the vibrator of my invention isshown in Figure 7. In this circuit the two stationary contacts areconnected across an inductance 25, the inductance being shunted by avariable condenser 26. I prefer to tune this combination of inductanceand capacity to,the frequency desired in the output of the system, andwe may take as an example 60 cycles. The inductance 25 is provided witha center lead 26' which, together with a lead 27 which is connected tothe movable contact 8, constitutes the D. C. input to the device. Outputleads 29 are extended from the terminals of the inductance 25, thealternating current being obtainable therefrom. The resistances 30-30,in series with condensers 31-31, are shunted between each of thestationary contacts and the movable contacts to absorb what smalltendency to are may be present. The circuit as shown is ideally adaptedfor use on ship board, as alternating current of approximately 160 voltsmay be obtained from the 100-110 volt D. C. ship supply. In use in theabove described circuit the motor speed is regulated to give the propernumber of contacts per second, i. e., 60 complete cycles per second.

In Figure 5, two of the contact tubes are shown attached to a singlemotor being simultaneously reciprocated in opposite directions. Such aconnection'is ideal where it is desired that one of the two contacttubes generate alternating current to energize a step up transformer.The other of the contact tubes may then be used to rectify the steppedup current. As the two contact tubes are connected to the same shakingsource, the rectifier is always in synchronism with the generator. Thecircuits used with this type of vibrator system, and others, are fullydisclosed and described in the application above referred to.

Figure 6 shows three of the contact tubes arranged to generate orrectify three phase alternating'currents. It should be pointed out inthis respect that the same general type of motor may be used as is shownin Figure 5, with three tubes on each crank arm whereby the simultaneousrectification and generation of three phase currents may beaccomplished.

While I have shown the use of a motor rotating a crank arm to give areciprocating motion to the contact assembly tube, it should bevunderstood that any means well known in the art may be used to impartthe proper reciprocating motion or shaking to the tube without departingfrom the spirit of the invention.

I claim:

1. In a mechanical vibrator system the combination of an envelope, apair of spaced opposed stationary contacts therein, inflexible supportsfor said contacts, a movable contact positioned between said stationarycontacts, a flexible nonresonant support for said movable contact,separate leads through said envelope for all of said contacts, and meansfor cyclically shaking said envelope to cause said movable contact toalternately touch said stationary contacts.

2. In a mechanical vibrator system the combination of an envelope, apair of spaced opposed stationary contacts therein, relatively shortinflexible supports for said contacts, a movable contact positionedbetween said stationary contacts. a flexible, nonresonant and relativelylong support for said movable contact, separate leads through saidenvelope for all of said contacts, and means for cyclically shaking saidenvelope to cause said movable contact to alternately touch saidstationary contacts.

3. In a mechanical vibrator system the combination of an envelope havinga reentrant stem terminating in a pinch, a pair of opposed and spacedstationary contacts inflexibly supported by said pinch, a movablecontact positioned between said stationary contacts, a support for saidmovable contact fastened to a clamp around said stem, said support beingof soft metal deformable beyond the elastic limit of the metal withinthe range of movement of said movable contact, separate leads throughsaid envelope for all of said supports, and means for cyclically shakingsaid envelope to cause said movable contact to alternately touch saidstationary contacts.

4. In a mechanical vibrator system the combination of an envelope havinga reentrant stem terminating in a pinch, a pair of opposed and spacedstationary contacts inflexibly supported by said pinch, a movablecontact positioned between said stationary contacts, a support for saidmovable contact fastened to a clamp around said stem, said support beingof soft metal deformable beyond the. elastic limit of the metal withinthe range of movement of said movable contact, separate leads throughsaid envelope for all of said supports, means for pivoting the stem endof said envelope, and means for imparting a regular reciprocating motionto the opposite end of said envelope to cause said movable contact toalternately touch said stationary contacts.

5. In a mechanical vibrator system the combination of an envelope havinga reentrant stem terminating in a pinch, a pair of opposed and spacedstationary contacts infiexlbly supported by said pinch, a movablecontact positioned between said stationary contacts, a support for saidmovable contact fastened to a clamp around said stem, said support beingof soft metal deformable beyond the elastic limit of the metal withinthe range of movement of said movable contact, separate leads throughsaid envelope for all of said supports, a pivot for the stem end of saidtube, the axis of the pivot being substantially in the plane of saidclamp and extending at right angles to the line of motion of saidmovable contact, and means for cyclically reciprocating said tube onsaid pivot to cause said movable contact to alternately touch saidstationary contacts.

6. In a mechanical vibrator system, a plurality of tubes having thereina movable contact adapted to touch a stationary contact on each sidethereof, each of said movable contacts being mounted on a supportdeformable beyond the elastic limit of the support within the range ofmotion of said movable contact, and means for imparting a cyclicallyreciprocating motion to each of said tubes in regular succession tocause the contacts in said tubes to be made and broken in apredetermined order.

PHILIP F. SCOFIELD.

